1. Field of the Invention
The present invention relates to a computed tomography apparatus such as an X-ray computed tomography apparatus with, for example, an X-ray high-voltage generating device incorporated in a rotating frame unit.
2. Description of the Related Art
An X-ray computed tomography apparatus comprises a rotating frame unit and a fixed section. In that conventional X-ray computed tomography apparatus, those component parts constituting an X-ray high-voltage generating device, such as a high-voltage transformer, inverter and input circuit sections are located at other than the rotating frame unit, for example, at the fixed section and an X-ray tube is placed in the rotating frame unit with a cable, such as a high-tension cable, connected between the X-ray high-voltage generating device and the X-ray tube.
In the case where all those component parts constituting the X-ray high-voltage generating device as set out above are arranged outside the rotating frame unit, the waveforms of the voltage, current, etc., of the X-ray tube can be readily measured, for example, irrespective of whether or not the rotating frame unit is rotated, by measuring the waveform of the high-voltage transformer, etc., of the high-voltage generating device by means of a measuring device. The waveform of each of the component parts constituting the X-ray high-voltage generating device can also readily be measured by means of the measuring device.
In an X-ray computed tomography apparatus of a type in which at least one of its component parts is mounted on the rotating frame unit and an electric power is supplied to the component parts in the apparatus which are mounted by a slip ring on the rotating frame unit, however, it is difficult to measure the waveforms, etc., of the component parts in the apparatus which are mounted on the rotating frame unit and, in particular, difficult to make such a measurement during the rotation of the rotating frame unit.
In the X-ray computed tomography apparatus of an X-ray high-voltage generating device separate type, the X-ray high-voltage generating device is located at a location isolated from an operation room where the apparatus body is placed, that is, at a location where there is no risk of an exposure with an X-ray. In the manufacturing process and service/maintenance checking, the apparatus has its various types of functions controlled by variable resistors, etc., on the board in the apparatus body. The installing of such an X-ray computed tomography apparatus in the medical institution such as hospitals, etc., often has to alter its house/building inner structure in view of a limitation on the mount space, etc., and therefore-the associated equipment has to be fitted for the installation of the apparatus involved.
In view of this limitation an X-ray computed tomography apparatus has been so modified that the apparatus body contains the aforementioned type of X-ray high-voltage generating device including a PC (print circuit) board, etc., and can be installed in a narrower space than before.
In this type of apparatus, the X-ray high-voltage generating device can be checked or adjusted for servicing and/or maintenance (hereinafter referred to simply as the checking, etc.) in the way as set out below.
(1) For safety, the driving unit for the rotating frame unit is turned OFF or that rotating frame mechanism is locked. In this state, various measuring devices (or equipments) are connected to an associated X-ray system circuit for measurement to be carried out. PA1 (2) For protection from an exposure with the X-ray the servicing engineer wears a protective clothing after an X-ray emission outlet has been shielded with a cover. PA1 (3) The X-ray system circuit is switched to a manual control mode by operating a corresponding switch on the PC board. PA1 (4) The tube voltage and tube current mode (X-ray tube) to be adjusted are selected by operating corresponding switches on the PC board. PA1 (5) The tube voltage and tube current are measured through test exposure with the X-ray. PA1 (6) A control variable resistor is adjusted on the PC board. PA1 (7) The tube voltage and tube current are set to their desired value by repeating the steps (5) and (6). PA1 (8) A manual control mode on the X-ray system circuit is switched to a remote control mode. The various measuring devices for measurement are removed and the rotating frame mechanism is unlocked and the frame is turned ON for operation. PA1 (1) There is a risk that the servicing engineer will suffer an X-ray exposure when adjusting the X-ray amount upon exposure test. PA1 (2) When the board on the X-ray high-voltage generating device is situated in a rather inaccessible position due to a restriction on the mounting of the X-ray high-voltage generating device relative to the apparatus body, the adjusting operation is both cumbersome and difficult. PA1 (3) Since the apparatus has a rotating section, there is a risk that the servicing engineer will be inadvertently hit by the rotating section during servicing operation.
Those operations between (1) to (8) are carried out while contacting with the frame.
The conventional X-ray computed tomography apparatus with the X-ray high-voltage generating device incorporated therein encounters the following problems during a manufacturing process and at the adjusting operation of the X-ray high-voltage generating device upon checking for servicing/maintenance.
Further as a system utilizing a signal transmission to the X-ray computed tomography apparatus (hereinafter referred to as an X-ray CT apparatus), a system (hereinafter referred to as a remote diagnostic system) is known which makes a connection, over a telephone line, between the X-ray CT apparatus installed at a site, such as a hospital, and a center side, such as a factory, for the remote control of the X-ray CT apparatus' function for a normal state to be achieved and this is done through a signal transfer of the rotating frame unit to and from an outside source. In the remote diagnostic system, the CT apparatus is normally routinely called from the center side over the telephone line and a diagnostic program on the CT apparatus side is started. A diagnostic examination is carried out, by the diagnostic program, for the normal function of the CT apparatus. The result of diagnostic examination is returned back to the center side again over the telephone line. The center side analytically examines the result of diagnostic examination and determines whether or not there is any abnormal state on the apparatus side. In the center side, the timing for sending a remote command to initiate the diagnostic program is not necessarily set in a routine way and a temporary diagnostic examination can also be carried out when receiving information corresponding to an abnormal state from a staff, for example, an operator and servicing engineers on the hospital side who work directly for operation and checking of the CT apparatus for servicing/maintenance.
However, since, in the conventional remote diagnostic system, the diagnostic program is initiated once any action, being either routine or temporary, is taken on the center side, a longer time period is required until an abnormal state is detected. In the routine diagnostic examination, for example, the diagnostic program is routinely initiated, but, in the event of any abnormal state occurring, a longer time is sometimes passed until the abnormal state is detected. In such a time, no prompt appropriate action can be taken against the occurrence of an abnormal state on the CT apparatus. This involves a continued abnormal state on the X-ray CT apparatus side, thus somewhat adversely affecting a medical action involved. In the temporary diagnostic examination, the center side has to be called, for example, from the hospital's operator, necessarily taking a longer time from the occurrence of the abnormal state to the appropriate action.